srinivas

• Jan 9th, 2007

 

Hi,

HIRE ,DIMENSIONAL DATA  IS STORED. NO  AGGRIGATE CALCULATIONS 

SCD WE R USING 3 WAYS

1.TYPE-1: IT'S MAINTAIN CURRENT DATA ONY

2.TYPE-2: IT'S MAINTAIN CURRENT DATA + COMPLET HOSTROY RECORDS

THESE R 3 WAYS  :1.FLAG DATA

                                  2.VERSION NO MAPPING

                                   3.EFFECTIVE DATE RANGE

3.TYPE-3: IT'S MAINTAIN CURRENT DATA +ONE TIME HISTROY

INCREMENTAL AGGRATION ARE STORED AGGRAGATE VALUES ACCORDING TO THE USER REQUIREMENTS

saibabu

 Profile Answers by saibabu 

• Jan 11th, 2007

 

hi,scd means 'slowly changing dimentions'since dimention table maintains master data ,the column values occationally changed .so dimention tables are called as scd tables and the fields in the scd tables are called as " slowly changing dimentions" .in order to maintain those changes we are following three types of methods.1. SCD TYPE1 this method maintains only current data2. SCD TYPE2 this method maintains whole history of the dimentions here three methods to identify which record is current one . 1> flag current data 2> version number mapping 3> effective date range3. SCD TYPE3 this method maintains current data and one time historical data.INCREMENTAL AGGRIGATIONsome requirements (daily,weekly ,every 15 days,quartly..........) need to aggrigate the values of certain colums. HERE U have to do the same job every time (according to requirement) and add the aggrigate value to the previous aggrigate value(previous run value) of those column.THE PROCESS CALLED AS INCREMENTAL AGGRIGATION.